Voltage regulator



Geiger-tube;

Patented Feb. 2, 1954 UNITED STATES PATENT OFFICE VOLTAGE REGULATOR.

,Johnt R.i-Niles, Detroit; IMich. ,A pucatiomMar 5., 1950,.seriamo.ism-27,9 10 Claims. 25083.6)

This invention relates to apparatus for testing-Geiger tubes and more particularlyito apparatus for providing a fast and reliable determination of the response characteristic of a Geiger-tube. The inventionis especially adapted toprovide an instantaneous indication of the voltage at which a predetermined Geiger tube response occurs. 7

In general, Geigeritubeshave-a hollowconductive oasing-whichis filled-with a suitable; gas-and a wire axially disposed within the casing .and insulated 'from the casing. The casing serves as the cathode and the-wire as the anode of the Geiger counter. Whena radioactive'einanation penetrates the tube; some .of the'gas molecules in thetuoe are ionizedand the ions are collected by the cathode andthe anode toform 2. current through the tube. 'When the voltage between the :anode and cathode is relatively 110w, the current changes considerably with small changesin-voltage. Atiiigher voltages, the current changes only 'slightlywith changes in voltage, This saturated region, designated as the plateau region, usually serves as the operating portion of the tube.

The response characteristics of a particular tube may change with time because ;of aging of the gas-in the tube and because of changes in the gas temperature and pressure. In other words, the cur entzt-hroughthe-Geiger tube may vary at dif-Eerent times even though the voltage on the -tuberemains constant. Thug/if "a constant current having :aprediaterm'ined value in the piateau region is desired for purposes of calibration, such as for calibrating other equipment usedwith Geiger-tubes. the currentcannot be obtained by maintaining "the voltage on the tube constant.

This invention provides apparatus for regulating the current through a Geiger tube by automatically varying the voltage applied'between the-anode and cathode of the tube. The invention also provides apparatus -for I instantaneously indicating-the voltage required to obtainthe particular current.

An object of this invention is to provide apparatus for regulati g the current through a above "indicated character for maintaining the current through a Geiger tube substantially consta-n-tEby automatically varying the voltage on the tl'ibe.

Still another object is-to provide, apparatus of the above indicated character for instantaneously indicating'the Voltage required-to maintain asubstantiallyjconstant current through a Geiger tube.

A still further object is to provide apparatus of the above indicated character which is simple, compact, efiicient and reliable.

Other objects and advantages of the invention will be apparent from a detailed-description of the invention and from the appended drawings and claims. 7

In the drawings the single-figure is a circuit diagram of one embodiment cf'theinvention.

Referring to the drawings, aGeigerituber enerally indicated at his provided. The tube I10 has a grounded conductive casing 12, which is filled with a suitable gas such as argon, and a Wire I i which is axially disposed within the casing in insulated relationship to the casing. The wire I 4 is connected through a relatively high resistance F6 to 'a'po-wer supply which will be described'in detail hereinafter and is also connected through a coupling capacitance 18 to the grid of a tubea'ill. Thecatho'de of thetubeZfl is grounded through a resistance 22 and is connectedto the grid through aresistance 2:4. The plate-is supplied through a potentiometer '26 with positive voltage from a suitable power supply, such as'a battery 26. The grid of a tube '30'is connected to the cathode of the tube 20; the cathode of the tube 30 is connected to a grounded resistance 3-2; and the plate is connected directly to the-batterY-ZB.

The movable arm 34 of the potentiometer 2'6 is connected through a coupling oapacitance'tfi to the grid of a tube 38. A resistance '46 is provided 'between the grid of the tube38 and ground and a resistance 4?. between the cathode and ground. The plate of the tube is supplied through a resistance '44 with positive voltage from the battery '28 and is coupledthrough a capacitance '46 to'theg-ridof a tube 48. The grid of the tube 48 is grounded through a resistance .50 and the cathode is directly grounded. A resistance '52 .is connected'between the plate of-the tube 48 and the battery 28. A capacitance-54 couplesthe plate of the tube 48 to the grid of atube 55. The grid of the tube E6 is grounded-througharesistance 5t and the plate is supplied with positive voltage from the battery 23. The cathodeis connected to ground through a resistance tfi and-the resistance '42 in series. I

In addition to beingconnected to the cathode resistance 24 is connected through a coupling capacitance 62 to the grid of a tube 64. A resistance 66 is connected between the grid of the tube 64 and the cathode, which is grounded. The plate is supplied with positive voltage through a resistance 68 and is coupled through a capacitance 16 to the grid of a tube 12, the grid being connected to a grounded resistance 14. A resistance 16 and a capacitance 18 are provided in parallel between the cathode of the tube 12 and ground and a resistance 80 is provided between the plate of the tube and the power supply 28.

The plate of the tube 12 is coupled through a capacitance 82 to the grid of a tube 84. Resistances 86 and 88 connect the grid of the tube 84 to the power supply 28 and to ground, respectively. The cathode of the tube 84 is grounded and the plate is supplied through a resistance 80 with positive voltage from the power supply 28. Capacitances 92 and 64 connect the grid and plate of the tube 84 to the plate and grid, respectively, of a tube 66. A resistance 68 is provided in parallel with the capacitance 94 and in series with a resistance I00. The resistance I is in series with a suitable power supply, such as a battery I02, the positive terminal of which is grounded. The cathode of the tube 96 is grounded and positive voltage from the battery 28 is applied to the plate through a resistance I04.

A coupling capacitance I06 is connected between the plate of the tube 96 and the grid of a tube I08. A resistance H0 is provided between the grid of the tube I08 and ground and a resistance II2 between the cathode and the negative terminal of the battery I02. Positive voltage from the battery 28 is applied to the plate of the tube I08 as well as to the plate of a tube I I4. The grid of the tube H4 is connected in series with resistances H6 and IIS and with the battery I02. The grid is also connected through a coupling capacitance I to the cathode of the tube 56.

The cathode of the tube H4 is connected to the cathode of the tube I08 and to the cathode of a diode I22, the plate of which is connected to the cathode of a diode I24. A storage capacitance I is connected between the cathode of the diode I24 and the resistance H8 and a resistance I26 and a capacitance I21 are provided in parallel between the capacitance and ground. The grid of a tube I28 is connected directly to the cathode of the diode I24. The plate of a diode I30 is connected to the common terminal between the capacitance I25 and the resistance I I8 and the cathode of the diode I30 is connected to the plate of the diode I24. The plate of the diode I24 is also coupled by a capacitance I32 to the cathode of the tube 56.

The plate of the tube I28 is supplied with positive voltage from the battery 28 and the cathode is connected through a resistance I34 to the negative terminal of the battery I02. A resistance I36 and a parallel arrangement of diodes I38 and I40 are provided in series between the cathode of the tube I26 and ground. The cathode of the diode I38 and the plate of the diode I40 are grounded, while a resistance I42 and a meter I44 are connected in series to the plate of the diode I36 and the cathode of the diode I40. One side of the meter I44 is grounded.

The cathode of the tube I28 is also connected to a stationary contact of a single-pole, doublethrow switch I46, the other stationary contact of the switch being grounded. A capacitance I48 is provided between the movable contact of the switch I46 and ground, and a meter I50, a resistance I52, a potentiometer I54, and a resistance I56 are connected in series between the movable contact of the switch I46 and the resistance I6. The resistances I56, I52 and I34 and the potentiometer I54 are chosen to provide zero voltage on the cathode of the tube I28. A capacitance I58 is connected to ground from the common terminal between. the resistances I56 and I6 and a capacitance I60 is connected between the movable contact I62 of the potentiometer I54 and the common terminal between the resistances I56 and I6.

The movable contact I62 of the potentiometer I54 is connected to the grid of a tube I64. The cathode of the tube I64 is connected to the movable Icontact I66 of a grounded potentiometer I68, which is connected to the positive terminal of a regulatedpower supply, such as a battery I10, adapted to supply a less positive voltage than the battery 26. l

The plate of the tube I84 is connected through a resistance I16 to the grid of a tube I18 and through a resistance I to the cathode of the tube I18. The cathode of the tube I18 is also connected to the common terminal between the resistances I56 and I6. The plate of the tube I18 is connected to a grounded filter capacitance I82 and to the cathode of a diode I8 4. The plate of the diode I84 is in series with a resistance I86 and the grounded secondary winding I88 of a power transformer I90.

With a source of known radioactivity acting upon the Geiger tube I0, a substantially constant number of radioactive emanations penetrate the tube. Each radioactive emanation causes some of the gas molecules to become ionized. The electrons are attracted to the wire I4 and the positive ions to the casing I2, producing on the tube a voltage pulse having an amplitude largely dependent upon the voltage difference between the wire I4 and the casing I2.

The voltage pulses on the Geiger tube I0 are amplified by a, plurality of amplifier stages in cascade arrangement, including the tubes 20, 30, 38 and 48. The pulses are then introduced to the cathode follower stage which includes the tube 56. The gain of the amplifier and cathode follower stages can be varied by adjustment of the movable arm 34 of the potentiometer 26 to give an integral amplification of the voltage pulse on the Geiger tube I0. For example, with a voltage pulse of 0.35 volt on the Geiger tube, a voltage pulse of 35 volts may be produced on the cathode of the tube 56 and introduced to the plate of the diode I24.

Normally, the voltage on the plate of the diode I24 is substantially the same as the negative voltage on the cathode of the diode because of the leakage provided by the diode I30. When positive pulses are applied to the plate of the diode I24 from the cathode of the tube 56, current fiows through a circuit which includes the battery 28, the tube 56, the capacitance I32, the diode I24, the capacitance I25 and the resistance H8. The current charges the capacitance I25 to a direct voltage substantially equal to the voltage on the cathode of the tube 56. This charge remains on the capacitance I25 during the intervals between successive pulses, but any charge that appears on the capacitance I32 is eliminated during pulse intervals by a discharge current which flows from the capacitance I82 through the capacitance I20, the resistance H6 and the diode I30. In this way; the capacitaneafl 5, istablertolreaohytheiiulla voltageromthez cathodesoir-the:tubefifi :durin 2 he: timew-thatthe;.veltageontthe cathodetof;thea;tub s remainsiconstantorciss increasing; 'Eor iexampl. with -5 :v.olts,-ataithercommonzterminalbetween e 5 the: capacitance and ztherireslstance; l l8;-;and-.-' with pulses having an amplitudesofi xvolts ape; pearingemthe cathcdes of the tubeifi; the voltage. on: the cathodeof; the; tube 124.- is: -5,0'.l-35,== -1,5 :'-V01tS-.l +4.0=-10=' volts :whenthe= amplitude ,of; the v nulsesiaonthe cathode of the tube-:Siincreases to ie-volts? V V v r rorprovidea .decreaseof the voltage-acrossthe; capacitance .425 ;corresponding;.to a decrease'ot; l5: pulsesamplitude on; the cathode oiithei tube .561; mplifier :stages including the tubes Bea-and l2, anda multivibrater including the tubes 84 9i; are provided Theiamplifieci pulsesirom, the: Geiger l-tuhe It} produce; negative outputsignals: 20. onsthel plate..-of the-tube: $.36 which when introdueed rtethe gridoflthenormally condu-ctingtube 1 [Oil -cause the-tube 1.08 to become cutofi. During thetimethat the tube-1881s conducting. a voltage isiproduced across the resistance H 2: to hring the. 25: cathcde. of the tube to; substantially ground po-= tential. When-the etuheiis, cut oil by the negate, 1 tiveesignalstfrom the-:plate-of, thetube- 9,6, the voltage onxthercathodei of the tube -,-Hl8-,star ts to; dropstovvards' theyvoltage on the; battery H22. 3:) Since the cathode voltage onv the-tube .H Hollows thecathode;moltageon-thetube 1i lit-,1 thetuhe; l l 4 starts toiccnduettwhen its cathode :voltageam proaches-tthe-negative bias on its-grid; r I

N.ormally the grid-.oithe taped this :biasedta 35 atvoltase substantiallyequal to the voltage; at the: comment terminals between that :capacitance 1-2 5;: nds-the resistance t 184cm examples-5Q volts- Withthepositire-veitagepulsesintrodueedgte the: d ofiitheatuba-l.ldlfrom the-cathodeeflthetllbel it 56,. thegricl-of thee-tube; H5 -beeomes less. healer: tivzeh, biased Whenlcurrent iiowszthrous'hithe; tube. LIA thescathodevoltage follows e the: said voltage and becomes dependent upon the tvoltage: on the cathode of the tube 56. Thus; with- 35;: volts onthecathods at the tubefet, th voltageon the -cathode oithetuhe l his?-5e+35=+l5volts Ire-the amplitude of; the-pulses.- on the; eathqde; of: the-tube 5 El tiecreases1- to 3&9: veltsa the voltage 1: thetcathodaof the tubes-l4; likewisesdecreasesstez --'5Q+ 3Q?\w2flvcits.-,-- However; rthe vol-tagesl on: the. cathcde f the diode liie-lrcm inszae *50+3i&v=.v-l5- .voltsheeause ref; theinabilitxt .f: thecapaci-tancalifiatadiseharge. Sincethe: l H v ageeon thecathede ofithetube is more estate: 5r fl -then. the voltageoni the cathoeleof; thexsdiode- L24; the; aeapacitaneep 1275 partially "discharges: through Zl J FLQHiRWhiQh-r inclutiesithe ieapaeitaueez; izt thetdiode l 22, lithe-resistance t2 zandtheyree eistance -li i8?- fIhe canaeitance: CEiSchar evcQnw tinnes. until thef-voltaeesz-onc the cathedestqiiithe. tuhes lzAeandj-i M become; 65113312.. The. calmed-850$ the diede tz i. therefore provides; atia-lhtimes an: indicati n direct volts therarnplitude ofzthepulses appearing; onthe: cnthedfi fithfi tushesfifie; it sincethevoltagegenrthe; QBtllhOdemOf-vthe tube 12s,: as indicated by thes'rmeter use; ioll'owszthe voltage-oaths -;cathcde of the-diode li zsa direct: voltage proportienalgl to: the amplitude-t or: the mllses; fromytha GeiQ-e tribe H! 1153 intmducetiz-ta the; erideoithe-:tube; 154. Thus,-: the pulse: amplitudes; increases the voltage:, on: the; grid." ofi thee tube letincreasesr causing the; current; through-imitative increases This produces-it's. veitaaedropaomth plateor:-thestuhsr-lfitand onv voltage 5 changesto in:

the:gridiofitheiztubeet.Ilecandianrinorease U emotive-resistance provided; bythe tub l8 n: the; series zcireuit-awhichz. includes-w the: .r.esistance.= e the tubal-84, 1 theztube H8; the resistances]fi; and the Geiger;tube -Ht.-- The resultant. decrease on the; Geiger; tube Y m causeatheinsthe 'zvoltage amplitude of; the pulses fronnthe, Geiger. tube: 0 decrease.

creases; the voltageront-the, gridA-Ofsthetuhe 6.4

decreases anclproducesaan increase; inthe;,vo1tsage, on; the-qGeiger-tube I 0: so; 3.57130; increase the amplitude of-ythe Geiger-tube pulses.

Inaoperation; themovablezcontact ofjthegswitchz l 45 1 isfirst-movedinto engagement with the right; shown in 'the accompanying;

s ationarycontact" drawing; Thearm lE;6*-of"the potentiometerris then; adjusted toprovidea predetermined voltage; 0n.=,.;the Geigem tube by,

gain: of the amplifiers. The; movable; contact of,

the-switch lat is thenarotated' totheleftstationw conta ctshcwn in thezaccompanying drawings: The circuitsthen; operatezto regulate;the;-ampli= tudeof; the pulses lfromlthefieiger tube by-vary ingthet oltageapplieslltosthe tubes l v Tl'iereis thus provideolapparatus for regulateing the amplitude: of

emanations penetrate: thetubei substantially; constant vby automatically; varying. the voltage applied to ime. tuber, Itshouldbe appreciatedathat the term fGeiger;tube-1 1 Played. above: andiasczused in; the, claims refers; to- :11;, ypes? of; radiationxdetectorss- For 1 example, the termewouldg include; ionizationchambersu Although this invention has been descrihedzlin connection; .Wi-th-i X certain specific; embodiments, the :IJITiIIFLiQIGSiHVOlVGd: arelsusoeptiblegof numer- OllSg-OthEZ-f applications that ,-wil1 rreadjlv occur: to; persons chilled;v inwthe art. The; intentionv iss therefore,.toabe'limited unis/as indicated. by the? w scopesoiuthevappended1claims."

Havin -thus describedtheeinventionmvhatcl: c1aim:.-as new-and desire to-secure-rbv-Lettersaabent:i s:

1: In combination; flzFGElQEi-i tubeaoperative'sto;

produce;- outputs pulses: havin ;.,-ampl.itudes=- olependent,upontthenvcltageson; applyingza..variablezavoltageeon the, Geigertubes a .:first; tube,-z algseeondt-tuhezla condenser, means? associated i withratheietzndenserzand. the? first and:

m second tubes. tqlproduce=aerow theacondensena.

voltagersub'stantially proportional tn the; ampli=,-.,. trident of: the; Geiger: tube pulses; and. meanstrfoni varying the ;-voltags.: on -;the;- Geiger; tube 1 in. ace; cm'dance:Withrchanges; in thcz condenserrzvoltage.

- 2.. In combination; .a Geiger:-tuheuoperativeato: produce; output: pulses having amnlitudes.;:;.de-=- pendent: uponsthe;voltagescn;theztub-eameansmn applying-;a;;-varsablevoltage-4cm the, Geiger: tubes a first; tube; .ascondenser adapted; torbezcha-rged;

; by outputr puises; from; the Geiger; tubesandi; con:

nested-tutti:

est it-nbeto provide-a; voltage; pmportional .;to

the; arnplitndeiioii-ontput pulses-sci:

' increasing strength;;.aeseeond tubeameans Afar;

preclucingi nsthe seeondstubesrzaevolita aernmpcne;

; tionah ta :the-ramplitude;='cf: outputrpulsee cases I V Similarly, if the pulse amplitudexdei varying: the effectivezrersistancez provided by the tube H8 The movable arm; lfiz oi the potentiometer I545 which" has 1a: resistance-compared: with the res.

controlof the voltageonsthefieiger:

arm. 34: to: vary; the} thentube', means for:

creasing strength, means connecting the condenser and the first and second tubes to produce across the condenser a voltage substantially proportional at all times to the amplitude of the Geiger tube pulses, and means for varying the voltage on the Geiger tube in accordance with changes in the condenser voltage from a predetermined value.

3. In combination, a Geiger tube adapted to provide output pulses upon the penetration of radioactive emanations, a condenser, a first tube connected to the condenser to provide a continuous circuit for charging the condenser to voltages proportional to the output pulses of increasing amplitude from the Geiger tube, a second tube connected to the condenser to provide a continuous circuit for discharging the condenser to voltages proportional to the output pulses of decreasing amplitude from the Geiger tube, and means responsive to the voltage across the condenser to vary the voltage on the Geiger tube for the maintenance of output pulses of a substantially constant amplitude from the tube.

4. In combination, a Geiger tube adapted to provide output pulses upon the penetration of radioactive emanations, a first tube, a second tube, a condenser connected to the first and second tubes, means for applying a voltage substantially proportional to the amplitude of the output pulses to the first and second tubes, means for charging the condenser through the first tube to a voltage substantially proportional to output pulses of increasing amplitude, means for discharging the condenser through the second tube to a voltage substantially proportional to output pulses of decreasing amplitude, means connected to the second tube for preventing the discharge of the condenser through the tube for output pulses of increasing amplitude, and means operative in accordance with the voltage on condenser to vary the voltage applied to the Geiger tube so as to maintain the output pulses from the Geiger tube substantially constant in amplitude.

5. In combination, a Geiger tube operative to produce output pulses having amplitudes dependent upon the voltage on the tube, a first circuit, a second circuit, means common to the first and second circuits, the first circuit being operative in accordance with pulses of increasing amplitude from the Geiger tube to provide an indication proportionate to the pulse amplitude across the common means, the second circuit being operative in accordance with pulses of decreasing amplitude from the Geiger tube to maintain an indication proportionate to the pulse amplitude across the common means, a voltage source, a variable impedance connected to the voltage source and the Geiger tube, and means for varying the value of the impedance in accordance with the indication from the common means to maintain the amplitude of the pulses through the Geiger tube substantially constant.

6. In combination, a Geiger tube operative to produce output pulses having amplitudes dependent upon the voltage on the tube, a first circuit, a second circuit, means common to the first and second circuits, the first circuit being opera-'- tive in accordance with pulses of increasing amplitude from the Geiger tube to provide an indication proportionate to the pulse amplitude across the common mean, means in the first circuit for preventing the operation of the circuit for pulses of decreasing amplitude, the second circuit being operative in accordance with pulses the r iii) of decreasing amplitude from the Geiger tube to maintain an indication proportionate to the pulse amplitude across the common means, means in the second circuit for preventing the operation of the circuit for pulses of increasing amplitude, a voltage source, a variable impedance connected to the voltage source and the Geiger tube, and means for varying the value of the impedance in accordance with the indication from the common means to maintain the amplitude of the pulses through the Geiger tube substantially constant.

7. In combination, a Geiger tube operative to produce output pulses having amplitudes dependent upon the voltage on the tube, a condenser, first means for charging the condenser to a value proportional to the amplitudes of the pulses from the Geiger tube when the pulse amplitudes are increasing, second means for discharging the condenser to a value proportional to the amplitudes of the pulses from the Geiger tube when the pulse amplitudes are decreasing, a voltage source, a variabl impedance connecting the voltage source to the Geiger tube, and mean operative in accordance with the charge on the condenser to vary the value of the variable impedance to maintain the output pulses from the Geiger tube substantially constant.

8. Apparatus for regulating the output or a Geiger tube, including, means for applying a voltage to the Geiger tube to produce output pulses in response to radioactive emanations, a condenser, means for charging the condenser in accordance with increased responses of the tube, means for preventing the condenser from discharging through the charging means during the periods of decreased response'of the tube, means for discharging the condenser in accordance with decreased responses of the tube, means for preventing the condenser from charging through the discharge means during the periods of increased response of the tube, and means operativ in accordance with the charge on the condenser to vary the voltage applied to the Geiger tube so as to maintain the tube current within predetermined limits.

9. Apparatus for regulating the output of a Geiger tube, including, means for applying a voltage to the Geiger tube to produce output pulses in response to radioactive einanations, a capacitance, means for introducing the output pulses to the capacitance to charge the capacitance to a value proportional to pulses of increasing amplitude, a normally conductive tube, means for cutting off the normally conductive tube durin the output pulses from the Geiger tube, means operative upon the cut-ofi of the normally conductive tube to provide a conductive path for the discharge of the capacitance during the periods of output pulses of decreasing amplitude until the charge on the capacitance is proportional to the amplitude of the output pulses, and means operative in accordance with the charge on the capacitance to vary the voltage applied to the Geiger tube so as to maintain the amplitude of the output pulses within predetermined limits.

10. Apparatus for regulating the output of a Geiger tube, including, means for applying a voltage to the Geiger tube to produce output pulses in response to radioactive emanations, a capacitance, means for introducing the output pulses to the capacitance to charge the capacitance to a value proportional to pulses of increasing amplitude, a first tube, means for cutting off the first tube during the output pulses from the Geiger tube, a second tube associated with the first tube.

means for introducing the output pulses to the second tube for the conductance of the tube during the cut-oil periods of the first tube, means for producing a discharge of the capacitance through the second tube during the conductance of the second tube for output pulses of decreasing amplitude until the charge on the capacitance is proportional to the amplitude of the output pulses, and means operative in accordance with the charge on the capacitance to vary the voltage applied to the Geiger tube so as to maintain the amplitude of the output pulses within predetermined limits.

JOHN R. NILES.

10 References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,443,857 Herzog June 22, 1948 2,465,938 Shonka Mar. 29, 1949 2,524,901 Fahrner Oct. 10, 1950 2,536,617 Weller Jan. 2, 1951 OTHER REFERENCES Radioactivity Meter, Bousquet, Electronics Industries, Sept. 1, 1946, pages 88-89.

Nucleonics, Oct. 1948, pages 46-61. 

